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Zhong Z.,Ningbo University | Dong Z.,Ningbo University | Yang L.,Ningbo University | Chen X.,Hangzhou Tea Research Institute | Gong Z.,Ningbo University
Experimental and Therapeutic Medicine | Year: 2012

Green tea catechins are known to function as anticancer agents via inhibition of carcinogenesis during the initiation, promotion and progression stages. Many potential mechanisms have been proposed, yet the precise mechanism of lung cancer prevention by green tea catechins remains unclear. microRNAs (miRs) are a class of 21-24 nucleotide small non-coding RNAs and play critical roles throughout cellular development and regulation. Emerging evidence demonstrates that tea catechins influence the expression of miRs in human cancer cells to inhibit tumorigenesis. Both let-7a-1 and let-7g were detected in the human lung cancer cells treated with tea catechins. The cell viability and cell cycle were analyzed after tea catechins treatment. In the present study, we found that tea catechins upregulated the tumor-suppressor miRs, let-7a-1 and let-7g, in lung cancer cell lines. The upregulation of let-7a/7g repressed the expression of their targets, C-MYC and the regulatory protein of LIN-28, at the mRNA and protein levels. Moreover, the cell growth assay indicated that tea catechins significantly inhibited cell proliferation, and the flow cytometric analysis revealed an increase in the number of cells in the G2/M phase and a decrease in the number of cells in the S phase after treatment with tea catechins. These observations suggest that green tea catechins mediate the inhibition of proliferation of lung cancer cells through the let-7 signaling pathway. Source

Ren G.,Anhui Agricultural University | Ren G.,Hangzhou Tea Research Institute | Wang S.,Anhui Agricultural University | Ning J.,Anhui Agricultural University | And 5 more authors.
Food Research International | Year: 2013

Near-infrared spectroscopy (NIRS) combined with chemometric tools was utilized as a rapid analysis method to assess quality and to differentiate geographical origins of black tea. A partial least squares (PLS) algorithm was employed for the calibration of models predicting the levels of caffeine, water extract, total polyphenols, and free amino acids, while a factorization method was proposed to trace black tea from different geographical origins. In the calibration set, the root mean squared error of cross validation (%) and the correlation coefficient (R) for caffeine, water extracts, total polyphenols and free amino acids were 0.102%, 0.654%, 0.552%, and 0.248% and 0.983, 0.977, 0.975, and 0.943, respectively. In the prediction set, the root mean squared error of prediction and R for the corresponding constituents were 0.160%, 0.685%, 0.594%, and 0.273% and 0.955, 0.962, 0.954, and 0.927, respectively. The identification accuracy for black tea from different geographical origins reached 94.3%. This study demonstrated that NIR spectroscopy can be successfully applied to rapidly determine the main chemical compositions and geographical origins of black tea. © 2012 Elsevier Ltd. Source

Zhang P.-Z.,Zhejiang University of Science and Technology | Ye M.-J.,Hangzhou Tea Research Institute | Hu W.-L.,Zhejiang University of Science and Technology | Wu J.,Zhejiang University
Wuli Huaxue Xuebao/ Acta Physico - Chimica Sinica | Year: 2016

The kinetics of the acid-catalyzed Smiles rearrangement reactions of 2,6-dimethoxy-2-pyrimidinyloxy- N-arylbenzylamine derivatives was investigated. The effects of initial concentrations of hydrochloric acid, solvent, temperature, and substituent on reaction rates were examined. The results show that the rates increase with an increase in the initial concentration of hydrochloric acid. The reactivity order is CH3OH > C2H5OH > CH3SOCH3 > CH3CN in a single solvent, but rates markedly increase in mixed CH3OH/H2O (1 : 1, V/V) and the apparent reaction rate constant (kobs) is 5.27 times that of methanol. The rates for the derivatives are found to increase with an increase in temperature at 25-45 °C, and no significant differences in activation energy (73.99-76.92 kJ·mol-1), activation enthalpy (71.57-74.38 kJ·mol-1), and Gibbs free energy (81.51-85.77 kJ·mol-1) are observed between them, except that there is difference in activation entropy (-24.38 - -47.11 J·K-1·mol-1). There is a good linear relationship between substituents and the apparent reaction rate constants, and it is speculated that electron-withdrawing groups in the benzene ring will increase the reaction rates. A relevant reaction mechanism is suggested. © Editorial office of Acta Physico-Chimica Sinica. Source

Tan R.,Shanghai University of Traditional Chinese Medicine | Tan R.,Hangzhou Tea Research Institute | Niu M.,Shanghai University of Traditional Chinese Medicine | Zhao J.,Shanghai University of Traditional Chinese Medicine | And 2 more authors.
Journal of Drug Targeting | Year: 2014

In order to improve the lymphatic targeting efficiency of anti-cancer agent vincristine sulfate (VCR), the poly (butylcyanoacrylate) nanoparticles (VCR-PBCA-NPs) were prepared by emulsion polymerization and modified superficially with Pluronic F127. These prepared nanoparticles with (F127-VCR-PBCA-NPs) and without surface modification (VCR-PBCA-NPs) were characterized and their lymphatic targeting efficiencies were evaluated in vitro and in vivo. The results showed that VCR was released more sustained from both kinds of VCR-loaded nanoparticles, compared with the VCR solution. The up-taking efficiency of VCR into raji cells was enhanced by F127-VCR-PBCA-NPs, compared with the VCR-PBCA-NPs or VCR solution. Lower clearance (CL) of VCR from the systemic circulation and higher lymphatic targeting efficiency of VCR were observed for F127-VCR-PBCA-NPs than the VCR-PBCA-NPs or VCR solution, and F127-VCR-PBCA-NPs showed greater antitumor efficacy than the VCR-PBCA-NPs or VCR solution in the human Burkitt's lymphoma (raji)-bearing nude mice. These findings suggest that superficially modified nanoscale carriers might be promising vehicles for chemotherapeutic agents in the treatments of metastatic tumors and malignant lymphoma. © 2014 Informa UK Ltd. All rights reserved: reproduction in whole or part not permitted. Source

Wu Q.-J.,Fujian Agriculture and forestry University | Dong Q.-H.,Fuzhou Huaming Tea Research Institute | Sun W.-J.,Fujian Agriculture and forestry University | Huang Y.,Fujian Agriculture and forestry University | And 2 more authors.
Journal of Agricultural and Food Chemistry | Year: 2014

This study aimed to construct objective and accurate analytical models of tea categories based on their polyphenols and caffeine. A total of 522 tea samples of 4 commonly consumed teas with different fermentation degrees (green tea, white tea, oolong tea, and black tea) were analyzed by high-performance liquid chromatography (HPLC) coupled with spectrophotometry, utilizing ISO 14502, as analytical tools. The content of polyphenols and caffeine varied significantly according to differently fermented teas, indicating that these active constituents may discriminate fermentation degrees effectively. By principal component analysis (PCA) and stepwise linear discriminant analysis (S-LDA), the vast majority of tea samples could be successfully differentiated according to their chemical markers. This study yielded three discriminant functions with the capacity to simultaneously discriminate the four tea categories with a 97.8% correct rate. In classification of oolong and other teas, there were one discriminant function and two equations with best discriminant capacity. Furthermore, the classification of different degrees of fermentation of oolong and external validation achieved the desired results. It is suggested that polyphenols and caffeine are the distinct variables to establish internationally recognized models of teas. Copyright © 2014 American Chemical Society. Source

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